Piano construction



Dec. 25, 1934. B. K, SETTERGREN PIANO CONSTRUCTION Filed May 25, 1954 MIW m N m T T A Patented Dec. 25, 1934 UNITED @FFEQE 3 Claims.

This invention relates to improvements in piano construction, and theobject thereof is to provide a piano frame with members so arranged asto eliminate contraction and expansion thereof and to rigidly supportthe sounding board to thereby increase the endurance of the tuning ofthe piano and improve its tone quality by elimination of vibration inthe frame members.

An illustrative embodiment of the invention is shown in the accompanyingdrawing, in which:-

Fig. l is an isometric View showing the bottom side of a piano frame towhich the invention is applied; and

Fig. 2 is a fragmentary bottom plan view of the bracing structure.

In the illustrations is shown a piano frame constituted of an inner rim1 which is connected at its forward ends by a cross-bar 2, and outer rim3 is disposed upon the exterior of the inner rim as in the usual pianoframe structure. A sounding board 4 provided with ribs 5 is securedabout its margin to the top of the inner rim and the cross bar as in theusual manner.

A series of struts 6, 7 and 8 spaced. apart positioned in the pianoframe so as to extend preferably in parallel relation with each otherfrom the cross bar at right angles thereto and terminate respectively attheir opposite ends against the inner face of the inner rim. to whichtheir corresponding ends are secured.

The struts 6 and 7 have disposed. therebetween spacers 9 and 10 by whichsaid struts are held definitely apart at points suitably distant fromtheir ends. Upon the outer faces of the struts 6 and 7 are disposedanchor plates 11 and 12 preferably of metal, the ends of which platesare connected through the'struts by cor esponding tie rods 13 and l lprovided with threaded nuts 15 which when tightened causes the struts tobecome bound tightly against said spacers.

A pair of anchor rods 16 are arranged in axial alinement with each otherand extend through the struts G and 7 and complemental anchor plates lland 12 at points preferably midway between the spacers 9 and 10 and areprovided with threaded nuts 17 and 18 disposed respectively against thecorresponding outer faces of the anchor plates and the inner faces ofthe complemcntal struts.

The outer ends of the anchor rods have cross heads 19 that are firmlysecured to the inner rim structure of the piano frame by means of bolts20 so that upon adjustment of the nuts 17 and 18 on the anchor rods 16 adefinite spaced relationship between the inner frame and the struts 6and 7 is established and the frame and struts are held securely againstrelative vibration. Also, in thus securing the inner frame and strutsfirmly together by means of the anchor rods, and holding the struts 6and 7 firmly in position with respect to each other the sounding boardis thereby sustained in a definite state of fixation about its marginwhereby the initial crown of the sounding board is substantiallypreserved.

I claim:

1. In a piano construction, a frame having inner and outer rims and across-bar connecting the end portions of said inner rim, a soundingboard secured about its margin to said frame, a series of struts spacedapart disposed in the frame extending respectively from the cross-bar tocorresponding opposite points on the inner rim, a pair of spacerspositioned between two of said struts, tie rods applied to the said twostruts so as to compress the spacers therebetween, and an anchor rod foreach of said two struts secured adjustably at one of its ends to thecorresponding strut, said struts being axially alined with each otherwnd connected at their other ends respectively to said frame atcorresponding opposite points thereon.

2. in a piano construction, a frame having a and a cross-bar conn ctingthe end portions thereof. a sounding board secured about its margin tosaid frame, struts spaced apart extending respectively from thecross-bar to corresponding opposite points on the frame, space-rspositioned between said struts, an anchor plate on the outer face ofeach strut opposite said spacers, tie rods connecting said platesthrough said struts disposed so as to compress said spacers between saidstruts, and axially alined anchor rods adjustably connected with saidstruts at their inner ends respectively at points between said spacersand connected at their outer ends respectively to said frame at coresponding opposite points thereon.

3. In a piano construction, a frame having a rim and a cross-barconnecting the end portions thereof, a sounding board secured about itsmargin to said frame, struts spaced. apart extending respectively fromthe cross-bar to corresponding opposite po nts on the frame, spacerspositioned between said struts, tie rods connecting said struts atpoints adjacent said spacers disposed so as to compress said spacersbetween said struts, and axially alined anchor rods adjustably connectedwith said struts at their inner ends r spectively at points between saidspacers and con nected at their outer ends respectively to said frame atcorresponding opposite points thereon.

13303 K. SETTERGREN.

